pratt



Nov. 13, 1923. 1,474,162 v A. D.- PRATT WATER TUBE BOILER Filed Oct- 16,1919 2 Sheets-Sheet 1 7! Q INVENTOR.

flrfur' fi. fraii BY fEQI/L ATTORNEYS.

Nov. 13,1923.

A. D. PRATT WATER TUBE BOILER Filed Oct. 16, 1919 2 Sheets-Sheet 2 IN VEN TOR.

A TTORNEYS.

Patented. Nov. 13, 1923.

UNITED STATES 1,474,152 PATENT OFFICE.

ARTHUR D. PRATT, OF NEW YORK, N. Y., ASSTG'NOR TO THE BABCOCK & WILCOXCOM- PA'NY, OF BAYONNE, NEW JERSEY, A. CORPORATION OF NEW JERSEY.

WATER-TUBE BOILER.

Application filed October 16, 1919. Serial No. 330,946.

T all whom it may concern Be it known that I, ARTHUR D. PRATT, a citizenof the United States, residingin the city of New York, borough ofManhattan, county and State of New York, have invented certain new anduseful Improvements in Wate-r-Tube Boilers, of which the followin is aspecification.

ly invention relates to a water tube boiler especially designed for usewhere there are large quantities of dust in the gases, and particularlyan arrangement by which the battles and tubes in such a boiler may berelieved of the accumulation of dust which will collect thereon. In thedrawings, Figure 1 is a side elevation partly in section of a boilerembodying one form of my invention; Fig. 2 is a side elevation, of theexterior of the furnace illustrated in Fig. 1, with some of the sidewall broken away; Fig. 3is a section on the line 3-3 of Fig. 2; Fig. fis a side view, partly in section, of the movable battles; and Fig. 5 isa side view of the movable bafiles. Similar reference numerals indicatesimilarparts in the several views.

The boiler illustrated comprises two transverse steam and water drums 1and 2 and a transverse mud drum 3, set parallel and connected by banksof tubes 4 and 5. The upper drums are connected by steam circulators 6and Water circulators 7 The latter support tiling which 'forms a roofover the cross passages from the uptake to the downtake and prevents thegases from striking the drums above the water line. Each bank is shownas having five rows of tubes, the upper ends of which are straight andare expanded into a stepped tube sheet, and the lower ends curved toproperly enter a circular mud drum. Two additional rows of verticaltubes 8 and 9 connect the mud drum with the upper drums, these two rowsforming a central bank. A bafile wall 10 is built in the space betweenthe rows of tubes Sand 9, the tubes forming a support for the wall whichextends upwardly from the mud drum to such height as to leave amplespace 7 for the products of' combustion to travel from the front to therear pass. The wall 10 is accessible for repairs through the doors 20,there being ample room for a man to work between the banks of tubes.

-The vertical battle wall 10 is located centrally between the main banksof tubes. Projecting from said baffle wall to the main banks of tubesare cross baflles 11, preferably of cast iron. A similar baffle 12 islocated between the bank of tubes 5 and the rear wall of the setting. Asone means by form which I have chosen for purposes of illustration, theshafts 121 are provided with weights 122-arranged to hold-the bafllenormally in operative position.

Suitable dusting doors 142 are provided through which an air or steamlance may be introduced for blowing the accumulated dust from thesurfaces of the tubes and also from the surface of the mud drum. Hoppers15 may be placed under the setting to receive the deposits. Any dustdeposited upon the baffles 11 and 12 may be readily discharged therefromby turning or shifting the battles, and the accumulation upon the tubesand the mud drum removed by an air or steam lance.

The boiler may be fired by any suitable furnaces, indicated at 16. Thegases enter the lower part of the front bank of tubes 4%, flow in ageneral upward direction over said tubes thence across above the bafflewall 10 and in a general downward direction over the tubes of bank, 5.The battles l1 and 12 causethe gases, in their general flow, to crossand recross the banks of tubes as indicated by the arrows. The gasesfinally escape. through the outlet 17. A seal 18 between the wall 19 andthe lower drum, prevents short circuiting of the gases.

The main steam outlet 21 is placed at the top and centre of the rearsteam and water drum. A feed water connection 22 dis charges into atrough in the rear drum and rid' of at frequent intervals by rotatingthe cross baffles 11 and 12 and removing the accumulation from thesurfaces of the tubes by an air or steam lance. Because of the large.tical and straight throughout a amount of dust in the gases, the tubest and 5 will also become coated, so that it is necessary to provide somemeans by which this dust or deposit may be readily removed from them. Tothis end, I have provided. scrapers 23 on each bank of tubes togetherwith means by which they may be moved along the tubes to remove thedeposits. In order that these scrapers shall be mosteflective, I preferto arrange the tubes as shown in Figure 1 withtheir upper ends straightand vertical so as to enable the scrapers to operate up to the pointwhere the tubes enter the upper drums l and 2. To this end, I preferablyprovide a stepped tube sheet for the upper drums, though it is obviousthat any other form of tube sheet which will permit the bank of tubes toenter the drum without curving't'he tubes, will answer my purposes.

As shown in Figure 1, the lower drum 8 is out of vertical alinement withthe upper drums and by making the tubes 4 and 5 vergreater portion oftheir length, beginning at the up per drums and by curving the lowerportions only in order to connect the tubes into the lower drum, Iprovide an arrangement by which the scrapers 23 may operate over thegreater portion of the length of the tubes and, at the same time, byreason of the curvature at the bottom of the tubes, the dust removed bythe scrapers 23 will fall away from the drum 3 into the hoppers 15.

The scrapers 28 may be of any suitable construction and, in the formillustrated, comprise cylindrical members to made in two or three partssurrounding each of the tubes, these cylindricalmembershavingprojections which engage between the plates of a frame 30 to cars31 of which are attached chains passing over chain wheels 33, 3-5- and35, the corresponding chain wheels on either side of the settin beingconnected by suitable shafts, and tie whole system of shafts and wheelsbeing turned, in the form illustrated, through suitable gearing by amotor 37, r

As will be seen by an ins iiection of Figure 1, the two sets of scraperscounterbalance each other; that is to say. when one is at the top of thetubes, the other is at the bottom. Rotation of the shaft of the motor37, first in one direction and then the other, will move the scrapers upand down the tubes to clean off the deposit and dust. In their upwardtravel, the scrapers move up to the upper drums l and 2.

The arrangement of the cylindrical members and the frame 30 supportingthem is such as to permit the removal of any of the cylindrical membersor the frame without disturbing the tubes with which they cooperate.

If desired, the scrapers 23 may be kept in continuous motion while theboiler is in operation. To this end, in" the form illustrated, one ofthe chains connected to the scrapers is provided with a pair of members8'71 and 87 2, arranged to contact alternately with a switch lever 88.The switch serves to reverse the motor 37. By this means, the switchlever is moved and the motor reversed as each scraper alternatelyreaches the limit of its upward stroke. Any other form of scraper movingmeans may be used, such as hand-operated chains, or the switch 38 may bethrown by hand.

Preferably, the baffles 11 and 12 are made to extend closely to thetubes 5 and 6. Unless provision were made for it, this would prevent thepassage of the scrapers To permit this, I arrange the scraper frames andthe ba'tlles so that contact between the two will serve to tilt theba-flle to permit the scrapers to pass, in the manner'shown in Fi 2. Assoonas the scraper has passed, weight 122 will return the bafiie tonormal position. 'lhe arrangement I have shown for this purpose isextremely simple, but obviously any suitable form of baflie operatindevice may be used.

lvhlle I have illustrated my invention in connection with a steamboiler, it will be understood that many of its parts may be applied alsoto any other form of water heater such as the economizer portion of aboiler and it will be understood that the term boiler as used in theappended claims refers notonly to a boiler proper but also to theeconomizer portion of a boiler.

.lVhat I claim and desire to secure by Let-' ters Patent of the UnitedStates is 2- l. A boiler having part of its heating surface formed ofvertically-extending straight tubes with laterally curved lowerportions,and scrapers permanently mounted upon the tubes and arranged to scrapethe surfaces of their straight portions, the curvat'ure of the tubesbeing such as to permit the soot thus scraped off to drop away be tweenthe lower )arts of 'thetubes, and mov able baflies having a portionthereof -nor mally located. in the path of movement of the scrapers, andadapted to be contacted by the scrapers to be moved out of the path ofthe scrapers. 1 a

2. A water tube boiler having a set of permanently mounted scrapersengaging the straight portions of some of its water tubes, means toreciprocate the scrapers. and a baflle having a portion thereof in thepath of the scrapers, said baffle being arranged to be moved by themotion of the scrapers to permit the scrapers to pass the baffle whenthe scrapers are moved in either direction.

3. A boiler having a vertical flue and a bank of tubes extendinglengthwise of the tubes. a battle extending from thewall of the flue tothe outermost of the tubes,

scrapers surrounding the outermost tubes and arranged to be moved up anddown thereon, said bafi'le being arranged to be moved by the motion ofthe scrapers to permit the scrapers to pass the baffle when the scrapersare moved in either direction.

41.. A boiler having a vertical flue and a bank of tubes extendinglengthwise of the tubes, a battle extending from the Wall of the flue tothe outermost of the tubes, scrapers surrounding the outermost tubes andarranged to be moved up and down thereon,

said baffle being pivotally mounted and arranged to be held normally inoperative position by gravity and to be moved out of 1 normal positionby the scrapers.

ARTHUR D. PRATT.

